Perpetual calendar.



No. '841,669. PATENTE!) JAN. 22, 1901. o. W. DAHL.

PBRPETUAL CALENDAR.

APPLICATION FILED DEG.19, 1905.

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UNTTED STATES PATENT OFFICE.

OLE W. DAHL, OF MALDEN. MASSACHUSETTS, ASSIGNOR OF ONE- THIRD TO HANS LUDVIG CHRISTIANSEN AND ONE-THIRD TO HARALD TIDEMAND, OF BOSTON, MASSACHUSETTS.

PERPETUAL CALENDAR.

Specification of Letters Patent.

Patented Jan. 22, 1907.

Application iled December 19, 1905. Serial No. 292,510.

To @ZZ whom t may concern:

Be it known that I, OLE W. DAHL, a citizen of the United States, residing in Malden, in the county of Middlesex and State of Massachusetts, have invented an Improvement in Perpetual Calendars, of which the following description, in connection with the accompanying drawings, is a specification, like characters on the drawings representing like parts. This invention relates to a perpetual calendar with which the day of the week may be made known when the year, month, and date of the month is given.

The invention is useful in ascertaining the day of the week on which any event may have taken place in the Christian era.

Figure l is an elevation of an apparatus embodying this invention; Fig. 2, a vertical section and elevation of the apparatus shown in Fig. l; Figs. 3 and 4, details to be referred to; Fig. 5, a developed view to be referred to; Fig. 6, a partial section and elevation of the apparatus, the section being taken on the line 6 c, Fig. 3.

The apparatus herein shown as embodying this invention consists of a plurality of rings or disks, herein shown as four in number and marked a b c d. The rings referredto are loosely mounted on a'sleeve or hub e, which is loose on a stationary shaft f, having screwed upon its opposite ends disks or heads g h.

The sleeve or hub e has fast on it a disk i, upon which the rings a Z) c d are superimposed. The sleeve or hub e is provided with seven longitudinally-extended ratchet-teeth j, with which cooperate pawls k, suitably fastened to the rings a b c d, one for each ring, whereby rotation in one direction of any one of the rings a l) c d will produce rotation of the sleeve or hub e and its attached disk. The rings a, b c ci are capable of being rotated independently of each other, and for this purpose said rings are separated from each other and from the disk i by washers n, which are stationary, and for this purpose said washers are provided with lugs o, which embrace or engage tie-bars p, connecting the heads g h.

Provision may and preferably will be made for insuring rotation of the rings a b c d in one direction only, and this may be accomplished by providing each washer n with a projection r, (see Figs. 4 and 6,) which engages one of a plurality of inclines s on the under side of the ring above said washer or in any other suitable manner. The rings a b c d are yieldingly held down by a spring 5 interposed between the head 7L and the uppermost ring d or in any other suitable manner.

The ratchet-hub e is provided with Aseven teeth j, one for each day of the week, and the disk i has applied to it the days of the week arranged in sequence. have their `circumferences subdivided into seven divisions, corresponding to the days of the week, said rings representing the century, year, month, and day of the month.

Tn the present instance the ring al has applied to its circumference the numerals indicative of the days of the month and running from l to 31, and may be designated the day-of-the-month ring. The ring b has applied to it the names of the month and may be termed the month-ring, and the disk i the day-of-the-week disk.

The rings c d have applied to their circumferences the numerals indicative of the years, the numerals on the ring c indicating the years in each century and the numerals on the ring d indicating the century according to both the Gregorian and the Julian calendars, and therefore the ring c may be termed the year-ring and the ring d the centuryring.

The numbers indicative of the century, year, month, and day are arranged in seven divisions on the respective rings which coperate to form seven columns, and the numbers indicative of the century, year, month, and day are arranged or grouped in such manner that all the years, months, and days contained within one column may correspond to one and the same week-day, and the groups in the next column to the right may correspond to the week-day next in order. Thus the months of September and December are in the same column, as shown in Fig. 5, be-

The rings a b c dl cause in a given year the corresponding days IOO days are grouped in one column; the second, ninth, &c., in the next column to the right, and the third, tenth, &c., in the next column, etc.

The numbers indicative of the days in each column are separated by seven, as plainly seen-in Fig. 5.

The numbers indicative of the centuries are arranged in columns, and the numbers in each column according to the Julian calendar are separated by seven and according to the Gregorian calendar are separated by four, because according to the Julian calendar corresponding dates occur on the same week-day every seventh century and according to the Gregorian calendar every fourth century. The numbers indicative of the years within a century are arranged in the columns so that the years within any given column are separated according to the numbers 6 5 6 11 6 5 6 11,7 as will be observed from inspection of Fig. 5. The years in each column are arranged in the sequence of 6 5 6 11, because in a period indicated by six years February 29 occurs once. In the period indi-- cated by live years February 29 occurs twice, and in the period of eleven years, which is the sum of 6 and 5,H February 29 occurs three times, which is the sum of 2 and 1. In the years thus separated in each column corresponding dates fall on corresponding week-days.

There is an exception from the above general rule. It is evident that in leap-years the months of January and February have a different relation to the rest of the months for other years, and therefore the said months are placed in different columns and distinguished, as by a different-colored ink, from the months of January and February of years not leap-years. l/Vhenever the week-day of a date in January and February of a leap-year is to be ascertained, the column containing the month in the distinguishing-ink is used. By reference to Fig. 5 the months of J anuary and February of non leap-years are arranged in the columns or spaces with October and March, respectively, while January and February of leap-years are placed in the columns or spaces April and August, respectively, because corresponding dates fall upon corresponding week-days.

By reason of the fact that the leap-year occurs every four years and by reason of the fact that one hundred is divisible by four the relation between the week-days of corresponding dates in two given centuries is the same throughout the centuries-as, for example, if the difference between August 5, 1804, and August 5, .1904, is two days it is also two days between January 1, 1860, and January l, 1960. Consequently the numbers indicative of the centuries can be applied to a separate ring, as d, and the numbers indicative of the years in a century can be applied to a separate ring, as c, and used with the number indicative of any century in either the Gregorian or Julian calendar. There is an exception to this in the Gregorian calendar in the case of January and February in secular years where one of the years is divisible by four hundred and not the other-as, for example, 2000 and 1900. In this case tne month indicative of leap-year is used in the first case-namely, with the 2000-and in the other the month in the non-leap-year column or space.

In England and North America dates of events before September 2, 1752, are ascertained by using the Julian calendar and after that date by using the Gregorian calendar.

In operation with tne apparatus the weekday on which any event may have taken place is ascertained by revolving the ring d until the proper century is opposite the space 20 in an inclosing cover or jacket 21, attached to the heads g 71,. During this revolution the ratchet-hub e is revolved with the ring (l, as is the disk t, attached to said hub.

rlhe year-ring c is next revolved until the proper year is brought opposite the space 20-that is, in the same column with the proper century or ring d. During the revolution of the ring c the ratchet-hub e and the disk i are moved with the ring c While the other rings remain stationary.

The month-ring b is next revolved until the proper month appears opposite the space, and last the day-of-the-month ring c is turned until the proper day of the month is brought opposite the space, and simultaneously will appear the day on the disk 'i on which the given date fell.

While the calendar is especially applicable for ascertaining the Week-day corresponding to anyparticular date in the past or future of the Christian era, the calendar can be used as a perpetual calendar, inasmuch as the ring a may be advanced the distance of one space for each successive day of the month, and the month-ring is turned to bring the next succeeding month opposite the space when the previous month has expired. At the expiration of the year the year-ring c is turned to bring the proper year o posite the space 20, and at the expiration o a century the ring d is turned to bring the next century-number opposite the space.

It is preferred to use the acket or cover 21 and leave the vertical opening or space 20; but it is not desired to limit the invention in this respect, as the jacket may be omitted. It will be observed that the seven spaces on the rings coperate to form seven columns'.

I have herein shown one construction or arrangement whereby the rotation of any one of the rings c l) 'c d effects simultaneous rotation of the week-day disk i; but I do not desire to limit my invention to the particular construction shown exce t as required by the scope of the appended c aims.

IOO

1. In a-calendar ofthe character described, in combination, a plurality of superimposed rotatable rings or disks having their circumferences subdivided into seven spaces, there being characters on two of said disks or rings in said spaces indicative of the centuries and years respectively, there being characters on another ring indicative of the months, there being characters on another ring indicative of the days of the month, and the names of the week-days on another ring or disk, and means for connecting the disk or ring bearing the names of the week-days with the other rings or disks, whereby the week-day disk is caused to rotate with each of the other rings or disks, substantially as described.

2. In a calendar ofthe character described, in combination, a plurality of superimposed disks or rings having their circumferences subdivided into seven spaces and provided with characters, one of said rings or disks having numerals arranged in sequence of seven to indicate centuries in the Julian calendar and having other numerals arranged in sequence of four to indicate centuries in the Gregorian calendar, and another disk coperating with the century-disk and having numerals arranged in each space in the sequence 6, 5, 6, 11," the other rings or 'disks having the names of the months, days of the week, and numerals indicative of the days in a month, substantially as described.

3. In a calendar oil the character described, in combination, a plurality of devices movable with relation to each other and having their surfaces subdivided into seven spaces, the spaces on one device being provided with numerals arranged in sequence of seven to indicate the centuries in the Julian calendar, and having other numerals in sequence of four to indicate centuries in the Gregorian calendar, another device having its spaces provided with numerals indicative of years and arranged in sequence of 6, 5, 6 and 11, another device having its spaces provided with the name of the months, another device having its spaces provided with numerals in sequence of seven to indicate the days of the month, and another device having its spaces provided with the names of the week-days, substantially as described.

4. In a calendar of the character described, in combination, a plurality of rings or disks having their-'circumference subdivided into seven spaces, one of said rings or disks having its spaces provided with numerals arranged in sequence of 6, 5, 6 and 11, to indicate years in a century, another disk or ring having the names of the months in its spaces, another disk or ring havin its spaces provided with numerals arrange in sequence of seven to indicate the days of the month, and another disk having its spaces provided with' the days of the week, means for supporting said disks, and means for effecting rotation of the day-disk with each of the other disks and of the said other disks independently oi each other.

5. In a calendar of the character described, in combination, a shaft, a hub or sleeve loose thereon and provided with seven ratchetteeth on its circumference, a disk fast to said -hub or sleeve to revolve therewith, a plurality of rings loosely mounted on said hub or sleeve and provided with pawls to engage the said ratchet-teeth, washers separating said rings, said disk and ringsfhaving their cirvcumferences subdivided into seven spaces which contain legends or characters for the 8o purpose specified. A

In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses.

OLE W. DAHL Witnesses:

HANs L. CHRIsTIANsEN, HARALD TIDEMAND. 

